This application is based on Application No. 2001-157435, filed in Japan on May 25, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a motor for use with a motorized power steering apparatus (hereinafter simply referred to as a motor) for assisting the steering force of a steering wheel of a vehicle.
2. Description of the Related Art
FIG. 9 is a perspective view of a motor 2 arranged in the neighborhood of an axle 1. As shown in FIG. 10, a worm wheel 4 is in meshing engagement with a worm 3 connected with the motor 2. Accommodated in a housing 60 are the worm 3 and the worm wheel 4 for transmitting a steering force of the motor 2 to a steering wheel of a vehicle (not shown). An O ring 61 is disposed between the motor 2 and the housing 60 for ensuring sealing therebetween.
FIG. 11 is a cross sectional side view of a known motor 2. FIG. 12 is an exploded view of the motor 2 of FIG. 11. The motor 2 includes a frame 5 of a cylindrical shape, a stationary element 6 fixed to the frame 5, a rotating element 8 comprised of a shaft 7 and a cylindrical magnet having an N magnetic pole and an S magnetic pole, a front bracket 9 mounted on one side of the frame 5 with a load side (i.e., steering wheel side) bearing 10 fixedly secured to its central portion, a rear bracket 12 mounted on the other side of the frame 5 with a counter load side (i.e., counter steering wheel side) bearing 11 fixedly secured to its central portion, a fastening bolt 13 connecting between the rear bracket 12 and the front bracket 9, a wire connection board 14 provided on the outer periphery of the counter load side bearing 11, a rotation sensor 15 of the resolver type fixedly secured to the rear bracket 12 for detecting the rotational angle of the rotating element 8, and a waterproof cap 16 mounted on the rear bracket 12 for covering the rotation sensor 15.
The stationary element 6 includes a stator core 17 having a plurality of axially extending slots (not shown) formed in a circumferentially spaced apart relation with respect to one another, a stator winding 18 wound around the stator core 17, and a bobbin 19 provided between the stator core 17 and the stator winding 18.
The rotation sensor 15 includes an oval-shaped rotor 45 fixed to an end portion of the shaft 7, and a stator 46 provided on the outer periphery of the rotor 45. The rotation sensor 15 is connected with a plurality of sensor signal wires 24 which penetrate through a grommet 25.
The wire connection board 14 has four doughnut-shaped stator side respective phase terminals 21. The stator side respective phase terminals 21 are connected with respective phase lead wires 23 of a U phase, a V phase and a W phase, which penetrate through a lead wire grommet 22.
With the motor 2 as constructed above, current flows from the respective phase lead wires 23 of the U phase, V phase and W phase to the stator winding 18, so that a rotating field is given to the stator winding 18, thereby causing the rotating element 8 to rotate. The rotating force of the shaft 7 is transmitted to the worm 3, which is spline connected with a boss 26 formed an end of the shaft 7, and thence to the worm wheel 4 in mesh with the worm 3, thereby assisting the steering effort of an operator applied to the steering wheel.
In the known motor 2, the outer peripheral portion of the motor 2 is constituted by the rear bracket 12 with the rotation sensor 15 fixedly mounted thereon, the frame 5 with the stationary element 6 fixed thereto, the front bracket 9 with the load side bearing 10 fixedly mounted thereon, and the waterproof cap 16. Thus, the motor 2 includes a lot of component members, and hence there arises a problem that the number of working processes of assembling the respective members with each other as well as the number of O rings 27, 28 and 29 arranged between the respective members increases.
Moreover, the stator side respective phase terminals 21 of the wire connection board 14 extend in a diametrical or radial direction, thus giving rise to another problem in that the diametrical or radial dimensions of the motor 2 become large.
In addition, there is also a further problem that each of the stator side respective phase terminals 21 is of a thin plate configuration, and there is only a narrow working space for directly connecting the respective phase lead wires 23 with the stator side respective phase terminals 21 through welding or the like, thus making the connecting work rather difficult.
Besides, there is a yet further problem that many sensor signal wires 24 are inserted into and extended through the grommet 25, and hence workability in inserting the sensor signal wires 24 into the grommet 25 is poor.
Still further, an additional problem is that separate formation of the grommet 25, through which the sensor signal wires 24 extend, and the grommet 22, through which the respective phase lead wires 23 extend, as illustrated in FIG. 13, accordingly increases the number of component members.
The present invention is intended to obviate the various problems as referred to above, and has for its object to provide a motor for use with a motorized power steering apparatus in which the number of component members can be reduced, and workability in assembling the component members can be improved, while enabling miniaturization of the entire motor.
Bearing the above object in mind, the present invention resides in a motor for use with a motorized power steering apparatus, including a frame of a bottomed cylindrical shape having an opening formed therein, a bracket fixed to the opening in the frame, a rotating element extending through the bracket and having a shaft rotatably supported by a frame side bearing fixedly mounted on the frame and a bracket side bearing fixedly mounted on the bracket, a stationary element fixedly attached to the frame at a location around an outer periphery of the rotating element and having a stator winding wound therearound, a rotation sensor provided on the bracket at one side of the bracket side bearing near a gear housing for detecting a rotational angle of the rotating element, and a plurality of sensor signal wires connected with the rotation sensor for supplying and receiving signals to and from the rotation sensor.
The above and other objects, features and advantages of the present invention will become more readily apparent to those skilled in the art from the following detailed description of preferred embodiments of the present invention taken in conjunction with the accompanying drawings.